[1/8] configure: Provide option to explicitly disable AVX2

Commit Message

Liam Merwick Aug. 30, 2018, 3:47 p.m. UTC

The configure script detects if the compiler has AVX2 support and
automatically sets avx2_opt="yes" which in turn defines CONFIG_AVX2_OPT.
There is no way of explicitly overriding this setting so this commit adds
two command-line options: --enable-avx2 and --disable-avx2.

The default behaviour, when no option is specified, is to maintain the
current behaviour and enable AVX2 if the compiler supports it.

Signed-off-by: Liam Merwick <[e-mail]>
Reviewed-by: Darren Kenny <[e-mail]>
Reviewed-by: Mark Kanda <[e-mail]>
---
 configure | 11 +++++++++--
 1 file changed, 9 insertions(+), 2 deletions(-)

Patch

diff --git a/configure b/configure
index 58862d2ae88a..8904a91715b3 100755
--- a/configure
+++ b/configure
@@ -427,7 +427,7 @@  usb_redir=""
 opengl=""
 opengl_dmabuf="no"
 cpuid_h="no"
-avx2_opt="no"
+avx2_opt=""
 zlib="yes"
 capstone=""
 lzo=""
@@ -1332,6 +1332,10 @@  for opt do
   ;;
   --disable-glusterfs) glusterfs="no"
   ;;
+  --disable-avx2) avx2_opt="no"
+  ;;
+  --enable-avx2) avx2_opt="yes"
+  ;;
   --enable-glusterfs) glusterfs="yes"
   ;;
   --disable-virtio-blk-data-plane|--enable-virtio-blk-data-plane)
@@ -1709,6 +1713,7 @@  disabled with --disable-FEATURE, default is enabled if available:
   libxml2         for Parallels image format
   tcmalloc        tcmalloc support
   jemalloc        jemalloc support
+  avx2            AVX2 optimization support
   replication     replication support
   vhost-vsock     virtio sockets device support
   opengl          opengl support
@@ -5127,7 +5132,7 @@  fi
 # There is no point enabling this if cpuid.h is not usable,
 # since we won't be able to select the new routines.
 
-if test $cpuid_h = yes; then
+if test "$cpuid_h" = "yes" -a "$avx2_opt" != "no"; then
   cat > $TMPC << EOF
 #pragma GCC push_options
 #pragma GCC target("avx2")
@@ -5141,6 +5146,8 @@  int main(int argc, char *argv[]) { return bar(argv[0]); }
 EOF
   if compile_object "" ; then
     avx2_opt="yes"
+  else
+    avx2_opt="no"
   fi
 fi